Which of the following statements is true? question 4 options: nuclear decay rates vary with the conditions of the reaction, but chemical reaction rates do not. chemical reaction rates vary with the conditions of the reaction, but nuclear decay rates do not. neither chemical reaction rates nor nuclear decay rates vary with the conditions of the reaction. both chemical reaction rates and nuclear decay rates vary with the conditions of the reaction.

The chemical reactions involve change in electron number or arrangement of electrons in an atom or atoms in a molecule. This leads to changes in chemical properties and hence a reaction takes place. These changes are dependent upon: Temperature, Pressure , other reaction conditions, the amount etc.

However nuclear reactions involves changes even at nuclear level (protons and neutrons). These changes are independent of reaction conditions.

Thus we can say that the following statement is true

Chemical reaction rates vary with the conditions of the reaction, but nuclear decay rates do not.

1. the question asks the most appropriate, which seems to rule out "all of the above." your choice appears to be the correct one.

2. the protocol described is good for identifying correlation, but not cause and effect. for cause/effect, you need to devise a protocol that will assign the treatment (or not) to groups that have essentially the same "demographics" with respect to all the other variables. your choice regarding control group seems appropriate. random assignment of treatment (choice d) may be appropriate also. (i think you can argue that b and d are just different descriptions of the same method.)

3. d will randomize the birds, but may not guarantee there are 10 in each group. e will do both, so seems the better choice.

comment on question 2

based on the problem statement, it seems clear that confident, attentive drivers are more likely to use daytime running lights. so, the protocol might need to be devised in such a way that the lights would be turned on or off without the driver's knowledge. (an attentive driver will figure it out.) assigning a confident, attentive driver to a group required to drive without running lights might mess with his/her confidence and attentiveness. you don't want your experiment to do that. (nor do you want the experiment to subject a driver to greater risk of accident as a consequence of driving without running lights.) experiments involving human safety are always problematic.

it's c. elements are placed in rows based on how may valencies electrons have.